Escape for lifting hook of diesel pile hammer



. (504/4420 [.Kezasemz June 27, 1961 L. L. FREDERICK ESCAPE FOR LIFTING 500K 0F DIESEL FILE HAMMER Filed April 14, 1958 W L i; i.

United States Patent Ofifice 2,990,023 Patented June 27, 1961 2,990,023 ESCAPE FOR LIFIING HOOK F DIESEL PILE HANIMER Leonard L. Frederick, Whippany, N.J., assignor to Mc- Kiernan-Terry Corporation, Harrison, NJ., a corporation of New Jersey Filed Apr. 14, 1958, Ser. No. 728,473 2 Claims. (Cl. 175150) The invention herein disclosed relates to pile hammers of the type covered in patent application Serial No. 493,758, filed March 11, 1955, Patent 2,882,690 issued April 21, 1959 in which diesel operation is initiated by lifting and dropping the ram in its cylinder by means of a trip block carrying a lifting hook which is automatically engaged with and disengaged from the ram by stops located at the bottom and top of the vertical travel of the trip block.

With such machines it is important that after releasing the ram the trip block be held in the upper range of its travel, that is above the lower trip stop, to avoid inadvertent projection of the lifting hook while the ram is in operation.

The general purpose of the present invention is to provide escape mechanism which will prevent injury if the lifting hook is accidentally or otherwise projected while the ram is in operation.

Further, related objects of the invention are to provide this protective mechanism in a simple, practical form readily applicable to existing machines.

Other desirable objects attained by the invention and the novel features through which such objects are accomplished are set forth and will appear in the course of the following specification.

The drawing accompanying and forming part of the specification is illustrative of a present commercial embodiment of the invention. Structure, however, may be modified and changed as regards the immediate illustration, all within the true intent and scope of the invention as hereinafter defined and claimed.

FIG. 1 in the drawing is a broken part vertical sectional view of a pile hammer having the invention incorporated therein, showing the trip block at the bottom of its stroke and the lifting hook projected in the ram engaging position;

FIG. 2 is a cross sectional view of the trip block and associated parts taken on substantially the plane of line 22 of FIG. 1;

FIG. 3 is a broken vertical sectional view of the lifting hook, showing it in full lines in projected and in broken lines in safety retracted positions;

FIG. 4 is a broken vertical sectional view on a smaller scale illustrating relation of the parts in the hook disengaging action;

FIG. 5 is a similar view showing the ram released and the trip block, with lifting hook released and retracted, raised to the top of its guide, into hammer lifting position.

In the illustration the trip block is shown at 7, operating in the vertical guideway 8 on the back of the cylinder 9 and carrying a lift hook 10 adapted to project through a slot 11 in the cylinder into an annular groove 12 in the ram 13 and thus into cooperative engagement with the lift shoulder 14 on the ram.

The lift hook 10 is in the form of a lever pivoted at the outer, base end at 15 in the trip block and arranged to be projected and retracted by a toggle made up of a trip lever 16 pivoted at its lower end in the block at 17 and pivotally connected at its upper end at 18 with the lower end of a failure link 19 pivotally connected at its upper end at 20 with the lift hook.

The trip lever 16 is automatically actuated at the lower and upper ends of the normal travel of the trip block by engagement of an inward projection 21 of the same with lower and upper stops 22, 23, FIGS. 1 and 4 respectively.

In FIG. 1 the toggle is shown in the straightened or extended position with the center pivot 18 past dead center and held so by engagement of the leverage extension 21 against stop shoulder 24 on the block. In this relation the toggle is locked in straightened position with the lift hook extended for supporting engagement with the ram and yieldingly held so by the spring pressed plunger 25 engaged with the cam extension 26 on the lower end of trip lever 16.

Lifting and dropping of the ram to start the diesel operation is then accomplished by raising the trip block with hoisting rope 27 to the FIG. 4 position whereupon extension 21 engages the upper stop 23 to unlock and rock the toggle into the broken or bent position shown in FIG. 5, retracting the hook and releasing the ram.

FIG. 5 illustrates the additional important feature of the trip block being raised to extreme upper position, after releasing the ram, into engagement with the hammer lifting stop 28 at the upper end of the trip block guide, as covered in above identified Patent 2,882,690.

In this relation, with the lift lever retracted clear of the ram and held so by engagement of spring pressed plunger 25 with angular shoulder 29 on the lower end of the trip lever the trip block may be held at the top or be lowered to any extent short of cooperation with the lower trip stop 22.

The present invention serves to protect the parts even though the trip block be lowered to the point of engagement of the trip lever extension 21 with the stop 22.

In practice this is accomplished by providing the lifting hook with a longitudinally extended slot 30 to form an elongated lost-motion bearing for the pivot pin 15 and by providing a helical expansion spring 31 seated in a longitudinal bore 32 in the hook and bearing against the inner side of the pivot pin to force the hook laterally inwardly toward the cylinder.

This construction while holding the hook normally advanced toward the cylinder as though fixedly centered on the pivot pin 15, permits the hook by pressure on the inner end of the same to be forced back into a retracted position clear of the ram.

This forced-back retracted position is indicated by the broken lines in FIG. 3 which show how engagement by the lower annular shoulder 33 of the ram will thrust the lifting hook outward against spring pressure to permit the ram to go by without injury to ram or lifting hook.

In the extended ram lifting position the hook lever is supported by the toggle in the locked, over center position, FIGS. 1, 3 and 4, on a slight downward incline. The upper, lifting edge of the lever is therefore finished off on a slight upward incline as indicated at 34 to effect a truly hooked, nonslipping engagement with the lifting shoulder 14 on the ram which, as shown in FIG. 1, is slightly undercut.

This construction, with the hook projected by the toggle is nonyielding in the upward load carrying direction of movement.

That portion of the inner end of the hook lever which projects through the slot in the cylinder is shown as rounded on an upwardly extending curve 35 providing a cam surface for engagement by the lower shoulder 33 of the ram.

Consequently upward pressure on this rounded cam portion by the shoulder 33 at the lower end of the annular groove in the ram is effective to force back the lifting hook, without injury to the hook or other parts. In being forced back in this way failure link 19 swings over on the center pivot 1-8 of the toggle, offering no opposition to this escape movement of the hook.

The construction is simple and strong and consists of but few parts.

The socket 32 for the escape spring may be bored in from the back end of the hook lever providing an opening 36 in the back of this lever, through which the spring may be introduced, after which the pivot pin 15 may be inserted through the bearings provided therefor and through the hook, while the spring is held compressed against the forward end of the spring socket. With this assembly the spring will be held in place by the pivot pin and back pressure of the spring on this pin will serve to hold the pin in place.

As a further precaution the pivot pin 15 may be annularly grooved in the midpoint, as indicated at 37, to a width equal to the diameter of the spring, so that the end of the spring will seat in this groove and prevent it from moving to one side through the elongated lost motion bearing slot. All pins are held captive by either the trip vertical guide ways 8, or the side walls of the trip body.

The mere act of assembly therefore secures the parts of the escape mechanism in coactive relation without extra fastenings or other parts.

The invention is of particular utility when in shutting down, the operator may release holding tension on the rope and permit the trip block to drop or lower before the ram has actually come to rest after fuel has been shut off. It is quite common for the ram to bounce a few times after fuel is shut ofi and there is a natural tendency on the part of the operator to release the trip block right after shutting off the fuel. There is also a tendency on the part of the operator to re-engage the trip while the ram is still bouncing after a misfire and during the starting operation of lifting and dropping the ram. Part damage is prevented in this case as well.

The present invention avoids breakage or other injury in such case because if the block is lowered to the extent Where the lift hook is projected as in FIG. 1, any upward impulse of the ram which would cause impact of the lower ram shoulder 33 with the hook will simply force back the hook to the broken line position shown in HQ. 3, whereupon the ram may continue in the upward movement, without injury to parts. In such continued upward movement the surface of the ram below shoulder 33 will hold back the hook and when the ram again lowers to the FIG. 1 position the hook will simply be projected again into the groove. Then, if the ram again fires or continues to fire this same escape cycle will simply be repeated.

If the trip block be lifted so that the extension 21 of the trip lever 26 will be clear of the lower stop 22 and the upper pivot 20 is snapped over behind dead center position of the toggle, the reaction from the outward thrust may be sufficient to snap the toggle over into the hook retracting position, shown in FIG. 5, whereupon the hook will be held in this retracted relation until again lowered into cooperation with the lower trip stop 22.

The invention constitutes a safety feature readily applicable to machines presently in use and adapted to protect and guard against injury to both machines and operators. Of particular importance, it can be applied to existing machines without altering their structural or operational features and without detracting from such machines in any way.

What is claimed is:

1. In a diesel hammer of the type having a ram operating as a piston in a cylinder and a trip block operable to lift the ram and tothen drop it to start the hammer, the ram having an annular groove with an undercut lifting shoulder at the top and a rounded abutment shoulder at the bottom of the same, the block having a liftinlg hook pivoted at its outer end on the block and adapted to be lifted into position projecting through a slot in the cylinder into engagement with said lifting shoulder by pivotally connected levers forming a toggle, one of said levers having a projecting trip arm engageable with a bottom stop to rock the toggle past dead center into a locked position supporting the lifting hook in the projecting ram lifting position and into engagement with an upper stop to break the toggle and lower the lifting hook into a position clear of the ram and a spring detent for yieldingly holding the toggle in the hook projecting and non projecting positions effected by engagement of the trip lever with said lower and upper stops, the improvement comprising an escape for preventing injury to the lifting hook and toggle mechanism in the event of the trip block being lowered and the hook being projected by engagement of the trip arm with the bottom stop while the ram is under impulse of an upward stroke, including a pivot pin pivotally and slidingly supporting the outer end of the lifting hook in the trip block, arranged to permit simple up and down swinging movement of the lifting hook about the pivot center and bodily movement of the hook toward and away from the ram and a spring yieldingly holding the lifting hook thrust toward the ram in the simple pivoting position described and yieldable to the thrust of the abutment shoulder at the bottom of the groove in the ram and the lower inner edge of the lifting hook having a rounded cam surface engageable by the rounded shoulder of the ram groove, whereby said lifting hook in the projected position described will be forced outwardly clear of the ram, saving said lifting hook mechanism from harm under conditions described.

2. The invention according to claim 1, in which said lifting hook is pivotally and slidingly supported by said pivot pin by having a slot engaged over the pin and in which said spring is seated in a longitudinally extending cavity in said hook, in thrust engagement wit-h said pivot pin.

References Cited in the file of this patent UNITED STATES PATENTS 2,177,935 Buck Oct. 31, 1939 2,305,772 Haage Dec. 22, 1942 2,633,832 Spurlin Apr. 7, 1953 2,822,690 Frederick Apr. 29, 1959 

